N-Acetylmannosamine is a monosaccharide that is used as a precursor in the chemical or enzymatic synthesis of the neuraminic acids found in glycolipids and glycoproteins.

Phosphorylcholine is a small haptenic molecule is found in a wide variety of organisms. Human hepatic tumors undergo an elevation in the concentration of phosphorylcholine as the principal metabolic change is observed .

1-Methylhistamine dihydrochloride is a major metabolite of histamine by histamine N-methyltransferase in the pathway of histidine metabolism.?It has been used as a biomarker of histaminergic system activity in the brains of Alzheimer's disease patients as well as those with hypersomnia and other neurological conditions.